Reverse water gas shift over In2O3–CeO2 catalysts

• The use of CeO2 enhances activities of In2O3 for RWGS.
• The selectivity to CO on RWGS over In2O3–CeO2 catalysts reaches 100%.
• The presence of CeO2 increases the surface areas of the In2O3–CeO2 catalysts.
• In2O3 particles in the In2O3–CeO2 catalysts show smaller size.
• More oxygen vacancies are created with the addition of CeO2.

In2O3 has been predicted as an excellent catalyst for CO2 conversion, for both hydrogenation to methanol at low temperature and reverse water gas shift (RWGS), whereas CeO2 promotes RWGS. In the present work, the promotion effect of CeO2 on RWGS over In2O3 was experimentally investigated. Characterizations show that the surface areas of the In2O3–CeO2 catalysts increase from that of pure In2O3 whereas the size of the In2O3 particles in the In2O3–CeO2 samples decreases as the fraction of CeO2 increases. In addition, the presence of CeO2 helps to create more, and stabilizes, oxygen vacancies, on which the dissociative hydrogen adsorption is enhanced and the amount of bicarbonate species resulting from activated CO2 adsorption is increased. The synergistic effect between In2O3 and CeO2 makes the In2O3–CeO2 catalysts exhibit enhanced activity for RWGS over the pure In2O3.

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